Oakland Zoo to release turtles to wild

WILDLIFE They will be released in marsh to bolster declining population

Carolyn Jones

Updated
10:24 pm PDT, Thursday, August 9, 2012

A western pond turtle swims in a tub at the Oakland Zoo, which plans to release the turtles into the wild.

A western pond turtle swims in a tub at the Oakland Zoo, which plans to release the turtles into the wild.

Photo: Stephen Lam, Special To The Chronicle

Photo: Stephen Lam, Special To The Chronicle

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A western pond turtle swims in a tub at the Oakland Zoo, which plans to release the turtles into the wild.

A western pond turtle swims in a tub at the Oakland Zoo, which plans to release the turtles into the wild.

Photo: Stephen Lam, Special To The Chronicle

Oakland Zoo to release turtles to wild

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Whoever said turtles are slow has obviously never been to the Oakland Zoo.

The zoo's 44 western pond turtles were scampering across their enclosure Thursday, clambering over each other like puppies and attempting to scale over the side to freedom.

And freedom is just a week away: Almost a year after they hatched, the rambunctious reptiles will be released next week in a remote Lake County bog as part of an ambitious project to study and save the steeply declining California native.

"We want to help these guys before it's too late," said zookeeper Ashley Terry. "It's exciting, but in a way it's hard to see them released. I love these little guys."

The turtle eggs were collected about a year ago by researchers at Sonoma State University, who are conducting a long-term study of California's only native aquatic turtle in hopes of learning why their numbers are declining so sharply.

Of special concern

The western pond turtle, with its shiny olive shell and webbed feet, once dabbled in creeks and lakes throughout the West. Now it's listed as endangered in Washington, threatened in Oregon and of special concern in California.

The main culprits are habitat loss and disease. But another turtle - the dreaded, nonnative red-eared slider - is also responsible. People buy red-eared sliders as pets, because when they're babies they're the size of a jawbreaker and cost about 25 cents, then release them into local ponds when they cease being cute.

Red-eared sliders have proliferated, are slightly more aggressive than their cousins and tend to hog all the available turtle food, biologists said.

In addition, juvenile western pond turtles are a favorite snack for just about everything with teeth - from skunks to snakes to big-mouth bass, scientists said.

"They're an all-you-can-eat dinner on predators' menus," said Dave Riensche, wildlife biologist at the East Bay Regional Park District, which is conducting its own study of the western pond turtle. "I opened up a bullfrog once and its stomach was full of baby pond turtles."

Back to the marsh

Sonoma State scientists send the turtle eggs to the Oakland and San Francisco zoos for upbringing, and after a year the turtles are released back in their marsh in Lake County. San Francisco's 38 turtles were released last week; Oakland's are headed back next Friday.

Since the program started four years ago, several hundred turtles have been successfully released back into the wild. Not only have the turtles been kept safe during the most perilous year of their lives, but researchers have also learned much about turtle biology, such as how temperature affects their growth, health and gender characteristics.

At the San Francisco Zoo, the baby turtles were on public display, a favorite attraction at the children's zoo.

"Turtles are one of the most ancient animals on the planet. They're like dinosaurs," said Jessie Bushell, assistant curator at the children's zoo. "To see these turtles grow and do well, it's fascinating for people."

The program has been so successful, in fact, that researchers are considering releasing turtles to Mountain Lake in San Francisco, among other sites.

In the East Bay, park district staff have affixed GPS devices to 20 western pond turtles in eastern Contra Costa County as a way to learn more about the cold-blooded animals and ultimately increase their numbers.

"Right now, we have a robust population of turtles in this one area," Riensche said. "We want to cure a problem before a cancer strikes. ... Our goal is to keep these guys around for many more years to come."